BOOK/chapter08/systemd.xml

   1 <?xml version="1.0" encoding="ISO-8859-1"?>
   2 <!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
   4   <!ENTITY % general-entities SYSTEM "../general.ent">
   5   %general-entities;
   6 ]>
   7
   8 <sect1 id="ch-system-systemd" role="wrap" revision="systemd">
   9   <?dbhtml filename="systemd.html"?>
  10
  11   <sect1info condition="script">
  12     <productname>systemd</productname>
  13     <productnumber>&systemd-version;</productnumber>
  14     <address>&systemd-url;</address>
  15   </sect1info>
  16
  17   <title>Systemd-&systemd-version;</title>
  18
  19   <indexterm zone="ch-system-systemd">
  20     <primary sortas="a-systemd">systemd</primary>
  21   </indexterm>
  22
  23   <sect2 role="package">
  24     <title/>
  25
  26     <para>The systemd package contains programs for controlling the startup,
  27     running, and shutdown of the system.</para>
  28
  29     <segmentedlist>
  30       <segtitle>&buildtime;</segtitle>
  31       <segtitle>&diskspace;</segtitle>
  32
  33       <seglistitem>
  34         <seg>&systemd-fin-sbu;</seg>
  35         <seg>&systemd-fin-du;</seg>
  36       </seglistitem>
  37     </segmentedlist>
  38   </sect2>
  39
  40   <sect2 role="installation">
  41     <title>Installation of systemd</title>
  42
  43 <!--
  44     <para>First, apply a patch to fix the build with GCC-10 and fix a segfault:</para>
  45
  46 <screen><userinput remap="pre">patch -Np1 -i ../systemd-&systemd-version;-gcc_10-fixes-2.patch</userinput></screen>
  47 -->
  48
  49     <para>Create a symlink to work around the xsltproc command not being installed:</para>
  50
  51 <screen><userinput remap="pre">ln -sf /bin/true /usr/bin/xsltproc</userinput></screen>
  52
  53     <para>Set up the man pages:</para>
  54
  55 <screen><userinput remap="pre">tar -xf ../systemd-man-pages-&systemd-version;.tar.xz</userinput></screen>
  56
  57     <para>Remove tests that cannot be built in chroot:</para>
  58
  59 <screen><userinput remap="pre">sed '177,$ d' -i src/resolve/meson.build</userinput></screen>
  60
  61     <para>Remove an unneeded group,
  62     <systemitem class="groupname">render</systemitem>, from the default udev
  63     rules:</para>
  64
  65 <screen><userinput remap="pre">sed -i 's/GROUP="render", //' rules.d/50-udev-default.rules.in</userinput></screen>
  66
  67     <para>Prepare systemd for compilation:</para>
  68
  69 <screen><userinput remap="configure">mkdir -p build
  70 cd       build
  71
  72 LANG=en_US.UTF-8                    \
  73 meson --prefix=/usr                 \
  74       --sysconfdir=/etc             \
  75       --localstatedir=/var          \
  76       -Dblkid=true                  \
  77       -Dbuildtype=release           \
  78       -Ddefault-dnssec=no           \
  79       -Dfirstboot=false             \
  80       -Dinstall-tests=false         \
  81       -Dkmod-path=/bin/kmod         \
  82       -Dldconfig=false              \
  83       -Dmount-path=/bin/mount       \
  84       -Drootprefix=                 \
  85       -Drootlibdir=/lib             \
  86       -Dsplit-usr=true              \
  87       -Dsulogin-path=/sbin/sulogin  \
  88       -Dsysusers=false              \
  89       -Dumount-path=/bin/umount     \
  90       -Db_lto=false                 \
  91       -Drpmmacrosdir=no             \
  92       -Dhomed=false                 \
  93       -Duserdb=false                \
  94       -Dman=true                    \
  95       ..</userinput></screen>
  96
  97     <variablelist>
  98       <title>The meaning of the meson options:</title>
  99
 100       <varlistentry>
 101         <term><parameter>-D*-path=*</parameter></term>
 102         <listitem>
 103           <para>These switches provide the location of binaries needed by
 104           systemd at runtime that have not yet been installed.</para>
 105         </listitem>
 106       </varlistentry>
 107
 108       <varlistentry>
 109         <term><parameter>-Ddefault-dnssec=no</parameter></term>
 110         <listitem>
 111           <para>This switch turns off the experimental DNSSEC support.</para>
 112         </listitem>
 113       </varlistentry>
 114
 115       <varlistentry>
 116         <term><parameter>-Dfirstboot=false</parameter></term>
 117         <listitem>
 118           <para>This switch prevents installation of systemd
 119           services responsible for setting up the system for
 120           the first time. They are not useful for LFS because
 121           everything is done manually.</para>
 122         </listitem>
 123       </varlistentry>
 124
 125       <varlistentry>
 126         <term><parameter>-Dinstall-tests=false</parameter></term>
 127         <listitem>
 128           <para>This switch prevents installation of the compiled tests.</para>
 129         </listitem>
 130       </varlistentry>
 131
 132       <varlistentry>
 133         <term><parameter>-Dldconfig=false</parameter></term>
 134         <listitem>
 135           <para>This switch prevents installation of a systemd unit that runs
 136           <command>ldconfig</command> at boot, which is not useful for source
 137           distributions such as LFS and makes the boot time longer. Remove it
 138           if the described feature is desired.</para>
 139         </listitem>
 140       </varlistentry>
 141
 142       <varlistentry>
 143         <term><parameter>-Droot*</parameter></term>
 144         <listitem>
 145           <para>These switches ensure that core programs and
 146           shared libraries are installed in subdirectories
 147           of the root partition.</para>
 148         </listitem>
 149       </varlistentry>
 150
 151       <varlistentry>
 152         <term><parameter>-Dsplit-usr=true</parameter></term>
 153         <listitem>
 154           <para>This switch ensures that systemd will work on
 155           systems where /bin, /lib and /sbin directories are not
 156           symlinks to their /usr counterparts.</para>
 157         </listitem>
 158       </varlistentry>
 159
 160       <varlistentry>
 161         <term><parameter>-Dsysusers=false</parameter></term>
 162         <listitem>
 163           <para>This switch prevents installation of systemd
 164           services responsible for setting up the
 165           <filename>/etc/group</filename> and
 166           <filename>/etc/passwd</filename> files. Both files
 167           were created earlier in this chapter.</para>
 168         </listitem>
 169       </varlistentry>
 170
 171       <varlistentry>
 172         <term><parameter>-Drpmmacrosdir=no</parameter></term>
 173         <listitem>
 174           <para>This switch disables installation of RPM Macros
 175           for use with systemd because LFS does not support RPM.</para>
 176         </listitem>
 177       </varlistentry>
 178
 179       <varlistentry>
 180         <term><parameter>-D{userdb,homed}=false</parameter></term>
 181         <listitem>
 182           <para>Remove two daemons that have dependencies that do not fit
 183           the scope of LFS.</para>
 184         </listitem>
 185       </varlistentry>
 186
 187     </variablelist>
 188
 189     <para>Compile the package:</para>
 190
 191 <screen><userinput remap="make">LANG=en_US.UTF-8 ninja</userinput></screen>
 192
 193     <para>Install the package:</para>
 194
 195 <screen><userinput remap="install">LANG=en_US.UTF-8 ninja install</userinput></screen>
 196
 197     <para>Remove an unnecessary symbolic link:</para>
 198
 199 <screen><userinput remap="install">rm -f /usr/bin/xsltproc</userinput></screen>
 200
 201     <para>Create the <filename>/etc/machine-id</filename> file needed by
 202     <command>systemd-journald</command>:</para>
 203
 204 <screen><userinput remap="adjust">systemd-machine-id-setup</userinput></screen>
 205
 206     <para>Setup the basic target structure:</para>
 207
 208 <screen><userinput remap="adjust">systemctl preset-all</userinput></screen>
 209
 210     <para>Disable a service that is known to cause problems with systems that
 211     use a network configuration other than what is provided by
 212     systemd-networkd:</para>
 213     <!-- Observed halting startup with dhcpcd handling the primary NIC -->
 214
 215 <screen><userinput remap="adjust">systemctl disable systemd-time-wait-sync.service</userinput></screen>
 216
 217     <para>Prevent systemd from resetting the maximum PID value which causes
 218     some problems with packages and units in BLFS:</para>
 219
 220 <screen><userinput remap="adjust">rm -f /usr/lib/sysctl.d/50-pid-max.conf</userinput></screen>
 221
 222   </sect2>
 223
 224   <sect2 id="contents-systemd" role="content">
 225     <title>Contents of systemd</title>
 226
 227     <segmentedlist>
 228       <segtitle>Installed programs</segtitle>
 229       <segtitle>Installed libraries</segtitle>
 230       <segtitle>Installed directories</segtitle>
 231
 232       <seglistitem>
 233         <seg>bootctl, busctl, coredumpctl, halt (symlink to systemctl),
 234         hostnamectl, init, journalctl, kernel-install, localectl, loginctl,
 235         machinectl, networkctl, portablectl, poweroff (symlink to
 236         systemctl), reboot (symlink to systemctl), resolvconf (symlink to
 237         resolvectl), resolvectl, runlevel (symlink to systemctl), shutdown
 238         (symlink to systemctl), systemctl, systemd-analyze,
 239         systemd-ask-password, systemd-cat, systemd-cgls, systemd-cgtop,
 240         systemd-delta, systemd-detect-virt, systemd-escape, systemd-hwdb,
 241         systemd-id128, systemd-inhibit, systemd-machine-id-setup,
 242         systemd-mount, systemd-notify, systemd-nspawn, systemd-path,
 243         systemd-repart, systemd-resolve (symlink to resolvectl), systemd-run,
 244         systemd-socket-activate, systemd-stdio-bridge, systemd-tmpfiles,
 245         systemd-tty-ask-password-agent, systemd-umount (symlink to
 246         systemd-mount), telinit (symlink to systemctl), timedatectl, and
 247         udevadm</seg>
 248         <seg>libnss_myhostname.so.2, libnss_mymachines.so.2,
 249         libnss_resolve.so.2, libnss_systemd.so.2,
 250         libsystemd.so, libsystemd-shared-&systemd-version;.so (in /lib/systemd),
 251         and libudev.so</seg>
 252         <seg>/etc/binfmt.d, /etc/init.d, /etc/kernel, /etc/modules-load.d,
 253         /etc/sysctl.d, /etc/systemd, /etc/tmpfiles.d, /etc/udev,
 254         /etc/xdg/systemd, /lib/systemd, /lib/udev, /usr/include/systemd,
 255         /usr/lib/binfmt.d, /usr/lib/environment.d, /usr/lib/kernel,
 256         /usr/lib/modules-load.d, /usr/lib/sysctl.d, /usr/lib/systemd,
 257         /usr/lib/tmpfiles.d,
 258         /usr/share/doc/systemd-&systemd-version;, /usr/share/factory,
 259         /usr/share/systemd, /var/lib/systemd, and /var/log/journal</seg>
 260       </seglistitem>
 261     </segmentedlist>
 262
 263     <variablelist>
 264       <bridgehead renderas="sect3">Short Descriptions</bridgehead>
 265       <?dbfo list-presentation="list"?>
 266       <?dbhtml list-presentation="table"?>
 267
 268       <varlistentry id="bootctl">
 269         <term><command>bootctl</command></term>
 270         <listitem>
 271           <para>Is used to query the firmware and boot manager settings</para>
 272           <indexterm zone="ch-system-systemd bootctl">
 273             <primary sortas="b-bootctl">bootctl</primary>
 274           </indexterm>
 275         </listitem>
 276       </varlistentry>
 277
 278       <varlistentry id="busctl">
 279         <term><command>busctl</command></term>
 280         <listitem>
 281           <para>Is used to introspect and monitor the D-Bus bus</para>
 282           <indexterm zone="ch-system-systemd busctl">
 283             <primary sortas="b-busctl">busctl</primary>
 284           </indexterm>
 285         </listitem>
 286       </varlistentry>
 287
 288       <varlistentry id="coredumpctl">
 289         <term><command>coredumpctl</command></term>
 290         <listitem>
 291           <para>Is used to retrieve coredumps from the systemd journal</para>
 292           <indexterm zone="ch-system-systemd coredumpctl">
 293             <primary sortas="b-coredumpctl">coredumpctl</primary>
 294           </indexterm>
 295         </listitem>
 296       </varlistentry>
 297
 298       <varlistentry id="halt">
 299         <term><command>halt</command></term>
 300         <listitem>
 301           <para>Normally invokes <command>shutdown</command> with the
 302           <parameter>-h</parameter> option, except when already in run-level 0,
 303           then it tells the kernel to halt the system; it notes in the
 304           file <filename>/var/log/wtmp</filename> that the system is being
 305           brought down</para>
 306           <indexterm zone="ch-system-systemd halt">
 307             <primary sortas="b-halt">halt</primary>
 308           </indexterm>
 309         </listitem>
 310       </varlistentry>
 311
 312       <varlistentry id="hostnamectl">
 313         <term><command>hostnamectl</command></term>
 314         <listitem>
 315           <para>Is used to query and change the system hostname and related
 316           settings</para>
 317           <indexterm zone="ch-system-systemd hostnamectl">
 318             <primary sortas="b-hostnamectl">hostnamectl</primary>
 319           </indexterm>
 320         </listitem>
 321       </varlistentry>
 322
 323       <varlistentry id="init">
 324         <term><command>init</command></term>
 325         <listitem>
 326           <para>Is the first process to be started when the kernel has initialized
 327           the hardware which takes over the boot process and starts all
 328           processes according to its configuration files. In this case, it starts
 329           systemd.</para>
 330           <indexterm zone="ch-system-systemd init">
 331             <primary sortas="b-init">init</primary>
 332           </indexterm>
 333         </listitem>
 334       </varlistentry>
 335
 336       <varlistentry id="journalctl">
 337         <term><command>journalctl</command></term>
 338         <listitem>
 339           <para>Is used to query the contents of the systemd journal</para>
 340           <indexterm zone="ch-system-systemd journalctl">
 341             <primary sortas="b-journalctl">journalctl</primary>
 342           </indexterm>
 343         </listitem>
 344       </varlistentry>
 345
 346       <varlistentry id="kernel-install">
 347         <term><command>kernel-install</command></term>
 348         <listitem>
 349           <para>Is used to add and remove kernel and initramfs images to and
 350           from /boot. In LFS, this is done manually.</para>
 351           <indexterm zone="ch-system-systemd kernel-install">
 352             <primary sortas="b-kernel-install">kernel-install</primary>
 353           </indexterm>
 354         </listitem>
 355       </varlistentry>
 356
 357       <varlistentry id="localectl">
 358         <term><command>localectl</command></term>
 359         <listitem>
 360           <para>Is used to query and change the system locale and keyboard layout
 361           settings</para>
 362           <indexterm zone="ch-system-systemd localectl">
 363             <primary sortas="b-localectl">localectl</primary>
 364           </indexterm>
 365         </listitem>
 366       </varlistentry>
 367
 368       <varlistentry id="loginctl">
 369         <term><command>loginctl</command></term>
 370         <listitem>
 371           <para>Is used to introspect and control the state of the systemd Login
 372           Manager</para>
 373           <indexterm zone="ch-system-systemd loginctl">
 374             <primary sortas="b-loginctl">loginctl</primary>
 375           </indexterm>
 376         </listitem>
 377       </varlistentry>
 378
 379       <varlistentry id="machinectl">
 380         <term><command>machinectl</command></term>
 381         <listitem>
 382           <para>Is used to introspect and control the state of the systemd Virtual
 383           Machine and Container Registration Manager</para>
 384           <indexterm zone="ch-system-systemd machinectl">
 385             <primary sortas="b-machinectl">machinectl</primary>
 386           </indexterm>
 387         </listitem>
 388       </varlistentry>
 389
 390       <varlistentry id="networkctl">
 391         <term><command>networkctl</command></term>
 392         <listitem>
 393           <para>Is used to introspect and configure the state of the network
 394           links configured by systemd-networkd</para>
 395           <indexterm zone="ch-system-systemd networkctl">
 396             <primary sortas="b-networkctl">networkctl</primary>
 397           </indexterm>
 398         </listitem>
 399       </varlistentry>
 400
 401       <varlistentry id="portablectl">
 402         <term><command>portablectl</command></term>
 403         <listitem>
 404           <para>Is used to attach or detach portable services from the local
 405           system</para>
 406           <indexterm zone="ch-system-systemd portablectl">
 407             <primary sortas="b-portablectl">portablectl</primary>
 408           </indexterm>
 409         </listitem>
 410       </varlistentry>
 411
 412       <varlistentry id="poweroff">
 413         <term><command>poweroff</command></term>
 414         <listitem>
 415           <para>Instructs the kernel to halt the system and switch off the computer
 416           (see <command>halt</command>)</para>
 417           <indexterm zone="ch-system-systemd poweroff">
 418             <primary sortas="b-poweroff">poweroff</primary>
 419           </indexterm>
 420         </listitem>
 421       </varlistentry>
 422
 423       <varlistentry id="reboot">
 424         <term><command>reboot</command></term>
 425         <listitem>
 426           <para>Instructs the kernel to reboot the system (see
 427           <command>halt</command>)</para>
 428           <indexterm zone="ch-system-systemd reboot">
 429             <primary sortas="b-reboot">reboot</primary>
 430           </indexterm>
 431         </listitem>
 432       </varlistentry>
 433
 434       <varlistentry id="resolvconf">
 435         <term><command>resolvconf</command></term>
 436         <listitem>
 437           <para>Registers DNS server and domain configuration with
 438           <command>systemd-resolved</command></para>
 439           <indexterm zone="ch-system-systemd resolvconf">
 440             <primary sortas="b-resolvconf">resolvconf</primary>
 441           </indexterm>
 442         </listitem>
 443       </varlistentry>
 444
 445       <varlistentry id="resolvectl">
 446         <term><command>resolvectl</command></term>
 447         <listitem>
 448           <para>Sends control commands to the network name resolution
 449           manager, or resolves domain names, IPv4 and IPv6 addresses,
 450           DNS records, and services.</para>
 451           <indexterm zone="ch-system-systemd resolvectl">
 452             <primary sortas="b-resolvectl">resolvectl</primary>
 453           </indexterm>
 454         </listitem>
 455       </varlistentry>
 456
 457       <varlistentry id="runlevel">
 458         <term><command>runlevel</command></term>
 459         <listitem>
 460           <para>Outputs the previous and the current run-level, as noted in the
 461           last run-level record in <filename>/var/run/utmp</filename></para>
 462           <indexterm zone="ch-system-systemd runlevel">
 463             <primary sortas="b-runlevel">runlevel</primary>
 464           </indexterm>
 465         </listitem>
 466       </varlistentry>
 467
 468       <varlistentry id="shutdown">
 469         <term><command>shutdown</command></term>
 470         <listitem>
 471           <para>Brings the system down in a safe and secure manner, signaling
 472           all processes and notifying all logged-in users</para>
 473           <indexterm zone="ch-system-systemd shutdown">
 474             <primary sortas="b-shutdown">shutdown</primary>
 475           </indexterm>
 476         </listitem>
 477       </varlistentry>
 478
 479       <varlistentry id="systemctl">
 480         <term><command>systemctl</command></term>
 481         <listitem>
 482           <para>Is used to introspect and control the state of the systemd system
 483           and service manager</para>
 484           <indexterm zone="ch-system-systemd systemctl">
 485             <primary sortas="b-systemctl">systemctl</primary>
 486           </indexterm>
 487         </listitem>
 488       </varlistentry>
 489
 490       <varlistentry id="systemd-analyze">
 491         <term><command>systemd-analyze</command></term>
 492         <listitem>
 493           <para>Is used to determine system startup performance of the current
 494           boot, as well as identify troublesome systemd units</para>
 495           <indexterm zone="ch-system-systemd systemd-analyze">
 496             <primary sortas="b-systemd-analyze">systemd-analyze</primary>
 497           </indexterm>
 498         </listitem>
 499       </varlistentry>
 500
 501       <varlistentry id="systemd-ask-password">
 502         <term><command>systemd-ask-password</command></term>
 503         <listitem>
 504           <para>Is used to query a system password or passphrase from the user,
 505           using a question message specified on the command line</para>
 506           <indexterm zone="ch-system-systemd systemd-ask-password">
 507             <primary sortas="b-systemd-ask-password">systemd-ask-password</primary>
 508           </indexterm>
 509         </listitem>
 510       </varlistentry>
 511
 512       <varlistentry id="systemd-cat">
 513         <term><command>systemd-cat</command></term>
 514         <listitem>
 515           <para>Is used to connect the STDOUT and STDERR outputs of a process
 516           with the systemd journal.
 517           </para>
 518           <indexterm zone="ch-system-systemd systemd-cat">
 519             <primary sortas="b-systemd-cat">systemd-cat</primary>
 520           </indexterm>
 521         </listitem>
 522       </varlistentry>
 523
 524       <varlistentry id="systemd-cgls">
 525         <term><command>systemd-cgls</command></term>
 526         <listitem>
 527           <para>Recursively shows the contents of the selected Linux control
 528           group hierarchy in a tree</para>
 529           <indexterm zone="ch-system-systemd systemd-cgls">
 530             <primary sortas="b-systemd-cgls">systemd-cgls</primary>
 531           </indexterm>
 532         </listitem>
 533       </varlistentry>
 534
 535       <varlistentry id="systemd-cgtop">
 536         <term><command>systemd-cgtop</command></term>
 537         <listitem>
 538           <para>Shows the top control groups of the local Linux control group
 539           hierarchy, ordered by their CPU, memory and disk I/O load</para>
 540           <indexterm zone="ch-system-systemd systemd-cgtop">
 541             <primary sortas="b-systemd-cgtop">systemd-cgtop</primary>
 542           </indexterm>
 543         </listitem>
 544       </varlistentry>
 545
 546       <varlistentry id="systemd-delta">
 547         <term><command>systemd-delta</command></term>
 548         <listitem>
 549           <para>Is used to identify and compare configuration files in
 550           <filename class="directory">/etc</filename> that override default
 551           counterparts in <filename class="directory">/usr</filename></para>
 552           <indexterm zone="ch-system-systemd systemd-delta">
 553             <primary sortas="b-systemd-delta">systemd-delta</primary>
 554           </indexterm>
 555         </listitem>
 556       </varlistentry>
 557
 558       <varlistentry id="systemd-detect-virt">
 559         <term><command>systemd-detect-virt</command></term>
 560         <listitem>
 561           <para>Detects whether the system is being run in a virtual
 562           environment, and adjusts udev accordingly.</para>
 563           <indexterm zone="ch-system-systemd systemd-detect-virt">
 564             <primary sortas="b-systemd-detect-virt">systemd-detect-virt</primary>
 565           </indexterm>
 566         </listitem>
 567       </varlistentry>
 568
 569       <varlistentry id="systemd-escape">
 570         <term><command>systemd-escape</command></term>
 571         <listitem>
 572           <para>Is used to escape strings for inclusion in systemd unit
 573           names</para>
 574           <indexterm zone="ch-system-systemd systemd-escape">
 575             <primary sortas="b-systemd-escape">systemd-escape</primary>
 576           </indexterm>
 577         </listitem>
 578       </varlistentry>
 579
 580       <varlistentry id="systemd-hwdb">
 581         <term><command>systemd-hwdb</command></term>
 582         <listitem>
 583           <para>Is used to manage the hardware database (hwdb)</para>
 584           <indexterm zone="ch-system-systemd systemd-hwdb">
 585             <primary sortas="b-systemd-hwdb">systemd-hwdb</primary>
 586           </indexterm>
 587         </listitem>
 588       </varlistentry>
 589
 590       <varlistentry id="systemd-id128">
 591         <term><command>systemd-id128</command></term>
 592         <listitem>
 593           <para>Generates and prints id128 strings</para>
 594           <indexterm zone="ch-system-systemd systemd-id128">
 595             <primary sortas="b-systemd-id128">systemd-id128</primary>
 596           </indexterm>
 597         </listitem>
 598       </varlistentry>
 599
 600       <varlistentry id="systemd-inhibit">
 601         <term><command>systemd-inhibit</command></term>
 602         <listitem>
 603           <para>Is used to execute a program with a shutdown, sleep or idle
 604           inhibitor lock taken, preventing an action such as a system shutdown
 605           until the process is completed.</para>
 606           <indexterm zone="ch-system-systemd systemd-inhibit">
 607             <primary sortas="b-systemd-inhibit">systemd-inhibit</primary>
 608           </indexterm>
 609         </listitem>
 610       </varlistentry>
 611
 612       <varlistentry id="systemd-machine-id-setup">
 613         <term><command>systemd-machine-id-setup</command></term>
 614         <listitem>
 615           <para>Is used by system installer tools to initialize the machine ID
 616           stored in <filename>/etc/machine-id</filename> at install time with a
 617           randomly generated ID</para>
 618           <indexterm zone="ch-system-systemd systemd-machine-id-setup">
 619             <primary sortas="b-systemd-machine-id-setup">systemd-machine-id-setup</primary>
 620           </indexterm>
 621         </listitem>
 622       </varlistentry>
 623
 624       <varlistentry id="systemd-mount">
 625         <term><command>systemd-mount</command></term>
 626         <listitem>
 627           <para>Is used to temporarily mount or automount disks.</para>
 628           <indexterm zone="ch-system-systemd systemd-mount">
 629             <primary sortas="b-systemd-mount">systemd-mount</primary>
 630           </indexterm>
 631         </listitem>
 632       </varlistentry>
 633
 634       <varlistentry id="systemd-notify">
 635         <term><command>systemd-notify</command></term>
 636         <listitem>
 637           <para>Is used by daemon scripts to notify the init system about status
 638           changes</para>
 639           <indexterm zone="ch-system-systemd systemd-notify">
 640             <primary sortas="b-systemd-notify">systemd-notify</primary>
 641           </indexterm>
 642         </listitem>
 643       </varlistentry>
 644
 645       <varlistentry id="systemd-nspawn">
 646         <term><command>systemd-nspawn</command></term>
 647         <listitem>
 648           <para>Is used to run a command or OS in a light-weight namespace
 649           container</para>
 650           <indexterm zone="ch-system-systemd systemd-nspawn">
 651             <primary sortas="b-systemd-nspawn">systemd-nspawn</primary>
 652           </indexterm>
 653         </listitem>
 654       </varlistentry>
 655
 656       <varlistentry id="systemd-path">
 657         <term><command>systemd-path</command></term>
 658         <listitem>
 659           <para>Is used to query system and user paths</para>
 660           <indexterm zone="ch-system-systemd systemd-path">
 661             <primary sortas="b-systemd-path">systemd-path</primary>
 662           </indexterm>
 663         </listitem>
 664       </varlistentry>
 665
 666       <varlistentry id="systemd-repart">
 667         <term><command>systemd-repart</command></term>
 668         <listitem>
 669           <para>Is used to grow and add partitions to a partition table when
 670           systemd is used in an OS image (e.g. a container).</para>
 671           <indexterm zone="ch-system-systemd systemd-repart">
 672             <primary sortas="b-systemd-repart">systemd-repart</primary>
 673           </indexterm>
 674         </listitem>
 675       </varlistentry>
 676
 677       <varlistentry id="systemd-resolve">
 678         <term><command>systemd-resolve</command></term>
 679         <listitem>
 680           <para>Is used to resolve domain names, IPV4 and IPv6 addresses, DNS
 681           resource records, and services</para>
 682           <indexterm zone="ch-system-systemd systemd-resolve">
 683             <primary sortas="b-systemd-resolve">systemd-resolve</primary>
 684           </indexterm>
 685         </listitem>
 686       </varlistentry>
 687
 688       <varlistentry id="systemd-run">
 689         <term><command>systemd-run</command></term>
 690         <listitem>
 691           <para>Is used to create and start a transient .service or a .scope
 692           unit and run the specified command in it. This is useful for
 693           validating systemd units.</para>
 694           <indexterm zone="ch-system-systemd systemd-run">
 695             <primary sortas="b-systemd-run">systemd-run</primary>
 696           </indexterm>
 697         </listitem>
 698       </varlistentry>
 699
 700       <varlistentry id="systemd-socket-activate">
 701         <term><command>systemd-socket-activate</command></term>
 702         <listitem>
 703           <para>Is used to listen on socket devices and launch a process upon
 704           a successful connection to the socket.</para>
 705           <indexterm zone="ch-system-systemd systemd-socket-activate">
 706             <primary sortas="b-systemd-socket-activate">systemd-socket-activate</primary>
 707           </indexterm>
 708         </listitem>
 709       </varlistentry>
 710
 711       <varlistentry id="systemd-tmpfiles">
 712         <term><command>systemd-tmpfiles</command></term>
 713         <listitem>
 714           <para>Creates, deletes and cleans up volatile and temporary files and
 715           directories, based on the configuration file format and location
 716           specified in
 717           <filename class="directory">tmpfiles.d</filename> directories</para>
 718           <indexterm zone="ch-system-systemd systemd-tmpfiles">
 719             <primary sortas="b-systemd-tmpfiles">systemd-tmpfiles</primary>
 720           </indexterm>
 721         </listitem>
 722       </varlistentry>
 723
 724       <varlistentry id="systemd-umount">
 725         <term><command>systemd-umount</command></term>
 726         <listitem>
 727           <para>Unmounts mount points</para>
 728           <indexterm zone="ch-system-systemd systemd-umount">
 729             <primary sortas="b-systemd-umount">systemd-umount</primary>
 730           </indexterm>
 731         </listitem>
 732       </varlistentry>
 733
 734       <varlistentry id="systemd-tty-ask-password-agent">
 735         <term><command>systemd-tty-ask-password-agent</command></term>
 736         <listitem>
 737           <para>Is used to list and/or process pending systemd password
 738           requests</para>
 739           <indexterm zone="ch-system-systemd systemd-tty-ask-password-agent">
 740             <primary sortas="b-systemd-tty-ask-password-agent">systemd-tty-ask-password-agent</primary>
 741           </indexterm>
 742         </listitem>
 743       </varlistentry>
 744
 745       <varlistentry id="telinit">
 746         <term><command>telinit</command></term>
 747         <listitem>
 748           <para>Tells <command>init</command> which run-level to change
 749           to</para>
 750           <indexterm zone="ch-system-systemd telinit">
 751             <primary sortas="b-telinit">telinit</primary>
 752           </indexterm>
 753         </listitem>
 754       </varlistentry>
 755
 756       <varlistentry id="timedatectl">
 757         <term><command>timedatectl</command></term>
 758         <listitem>
 759           <para>Is used to query and change the system clock and its settings
 760           </para>
 761           <indexterm zone="ch-system-systemd timedatectl">
 762             <primary sortas="b-timedatectl">timedatectl</primary>
 763           </indexterm>
 764         </listitem>
 765       </varlistentry>
 766
 767       <varlistentry id="udevadm">
 768         <term><command>udevadm</command></term>
 769         <listitem>
 770           <para>Is a generic udev administration tool which controls the udevd
 771           daemon, provides info from the Udev hardware database, monitors
 772           uevents, waits for uevents to finish, tests udev configuration, and
 773           triggers uevents for a given device</para>
 774           <indexterm zone="ch-system-systemd udevadm">
 775             <primary sortas="b-udevadm">udevadm</primary>
 776           </indexterm>
 777         </listitem>
 778       </varlistentry>
 779
 780       <varlistentry id="libsystemd">
 781         <term><filename class="libraryfile">libsystemd</filename></term>
 782         <listitem>
 783           <para>Is the main systemd utility library</para>
 784           <indexterm zone="ch-system-systemd libsystemd">
 785             <primary sortas="c-libsystemd">libsystemd</primary>
 786           </indexterm>
 787         </listitem>
 788       </varlistentry>
 789
 790       <varlistentry id="libudev">
 791         <term><filename class="libraryfile">libudev</filename></term>
 792         <listitem>
 793           <para>Is a library to access Udev device information</para>
 794           <indexterm zone="ch-system-systemd libudev">
 795             <primary sortas="c-libudev">libudev</primary>
 796           </indexterm>
 797         </listitem>
 798       </varlistentry>
 799
 800     </variablelist>
 801
 802   </sect2>
 803
 804 </sect1>